CD274 and neoplasm: PD-L1 expression is a logical predictor of responsiveness to PD-1/PD-L1 inhibitors as it is mechanically essential in the immune checkpoint pathway.21 Two recent meta-analyses have shown the response to immunotherapy increases proportionally with the extent of PD-L1 expression in TCs.44–46 As a general model, the ORR is 2 to 3 times higher for PD-L1-positive patients.45 46 Moreover, patients with PD-L1-positive tumours have higher survival rates when treated with ICIs.45 46